Paper-feeding mechanism capable of adjusting skew print media

ABSTRACT

A paper-feeding mechanism includes an input roller for picking up a print medium, a pinch input roller for nipping the print medium with the input roller, and a deskew shutter installed on a side of the input roller and the pinch input roller. The deskew shutter includes a flexible pad for blocking the print medium before the print medium is nipped by the input roller and the pinch input roller so as to adjust the skew print medium. The paper-feeding mechanism further includes an elastic component connected to the deskew shutter for providing an elastic force to the deskew shutter. The deskew shutter is connected to the elastic component in a rotatable manner.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper-feeding mechanism, and more particularly, to a paper-feeding mechanism capable of adjusting skew print media.

2. Description of the Prior Art

When printing to paper with a fax machine, a printer, or a multi-function product, a paper-feeding mechanism is utilized for feeding paper one sheet at a time into machines so as to proceed to faxes, printouts, copies, and so on. For preventing skew images on print media, several methods are applied to get rid of skew feed of print media due to skew position or tolerance.

There are two kinds of methods for adjusting the skew print media. One is a close loop deskew method, and the other is an open loop deskew method. For the close loop deskew method, U.S Pat. No. 5,169,140 and U.S Pat. No. 5,278,624 disclose a method for detecting relative position of the leading edge of the print media by sensors and transmitting a detecting result to motors. The skew print media can be adjusted by controlling speed of the two motors. However it not only increases cost due to many components of the sensors and the motors but also complicates the control circuit for processing signals transmitted from the sensors and transmitting corresponding signals to the motors.

There are two kinds of manners for adjusting the skew print media with the open loop deskew method. U.S Pat. No. 6,805,347B1 and U.S Pat. No. 5,678,488 disclose a method for making the print media buckle to reduce rigidity of the print media so as to adjust the print media easily by controlling a gear set to stop rotating or to reverse. However it reduces transmission speed of the print media because it takes time to control the gear set to reverse first and to forward then. There is no need to stop or reverse the gear set halfway and the paper-feeding process continues with the other manner. Please refer to FIG. 1 and FIG. 2. FIG. 1 is a diagram of a paper-feeding mechanism 10 when a print medium 12 has not pushed a deskew shutter 14 in the prior art. FIG. 2 is a diagram of the paper-feeding mechanism 10 when the print medium 12 has pushed the deskew shutter 14 in the prior art. The paper-feeding mechanism 10 includes the deskew shutter 14, an elastic component 16, an input roller 18, a pinch input roller 20, a paper tray 22, and a pickup roller 24. The paper tray 22 is for positioning the print medium 12. The pickup roller 24 is installed in front of the paper tray 22 for picking up the print medium 12 to the input roller 18 and the pinch input roller 20. The input roller 18 is for picking up the print medium 12. The pinch input roller 20 is for nipping the print medium 12 with the input roller 18. The deskew shutter 14 is installed on a side of the input roller 18 and the pinch input roller 20 for blocking the print medium 12 before the print medium 12 is nipped by the input roller 18 and the pinch input roller 20 so as to adjust the skew print medium 12. An end of the elastic component 16 is connected to the deskew shutter 14, and the other end of the elastic component 16 is connected to a fixed end, such as a housing for covering internal components of the paper-feeding mechanism 10. The elastic component 16 provides an elastic force to the deskew shutter 14. The deskew shutter 14 is connected to the elastic component 16 in a rotatable manner. The elastic component 16 can be a spring.

First the print medium 12 is picked up by the pickup roller 24, passes through a paper-feeding route of the paper tray 22, and hits the deskew shutter 14. The print medium 12 has to overcome the elastic force provided by the elastic component 16 connected to the deskew shutter 14 so that the print medium 12 is capable of pushing the deskew shutter 14 to enter nip location of the input roller 18 and the pinch input roller 20. If the print medium 12 is positioned exactly, the print medium 12 can overcome the elastic force provided by the elastic component 16 so that the print medium 12 is capable of pushing the deskew shutter 14 to enter nip location of the input roller 18 and the pinch input roller 20. Then the print medium 12 is nipped by the input roller 18 and the pinch input roller 20 together and transmitted to a print area. If the print medium 12 is skew, one leading edge of the print medium 12 hits the deskew shutter 14 first but the leading edge of the print medium 12 can not overcome the elastic force provided by the elastic component 16 so that the print medium 12 is not capable of pushing the deskew shutter 14 to enter nip location of the input roller 18 and the pinch input roller 20 on the instant. After the print medium 12 deforms so that two leading edges of the print medium 12 hit the deskew shutter 14, the print medium 12 can overcome the elastic force provided by the elastic component 16 so that the print medium 12 is capable of pushing the deskew shutter 14 to enter nip location of the input roller 18 and the pinch input roller 20. Then the print medium 12 is nipped by the input roller 18 and the pinch input roller 20 together and transmitted to the print area.

Compared with other methods for adjusting the skew print medium, the paper-feeding mechanism 10 with the deskew shutter 14 and the elastic component 16 has advantages of low cost, fast transmission speed, and a simple control circuit. However it is possible that the print medium 12 still can not overcome the elastic force provided by the elastic component 16 so that the print medium 12 is not capable of pushing the deskew shutter 14 after the print medium 12 deforms so that two leading edges of the print medium 12 hit the deskew shutter 14 due to the light print medium. It causes a paper jam problem. Furthermore, as shown in FIG. 2, when the print medium 12 overcomes the elastic force provided by the elastic component 16 to push the deskew shutter 14 and to enter nip location of the input roller 18 and the pinch input roller 20, the print medium 12 strays from a normal paper-feeding route easily because of reducing included angle between the print medium 12 and the deskew shutter 14 when the deskew shutter 14 rotates so as to reduce a holding force applied on the print medium 12 by the deskew shutter 14. It also causes a paper jam problem. There is a need to find out a solution for both reducing cost and adjusting the skew print medium effectively.

SUMMARY OF THE INVENTION

It is therefore a primary objective of the claimed invention to provide a paper-feeding mechanism capable of adjusting skew print media for solving the above-mentioned problem.

According to the claimed invention, a paper-feeding mechanism includes an input roller for picking up a print medium, a pinch input roller for nipping the print medium with the input roller, and a deskew shutter installed on a side of the input roller and the pinch input roller. The deskew shutter includes a flexible pad for blocking the print medium before the print medium is nipped by the input roller and the pinch input roller so as to adjust the skew print medium. The paper-feeding mechanism further includes an elastic component connected to the deskew shutter for providing an elastic force to the deskew shutter. The deskew shutter is connected to the elastic component in a rotatable manner.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a paper-feeding mechanism when a print medium has not pushed a deskew shutter in the prior art.

FIG. 2 is a diagram of the paper-feeding mechanism when the print medium has pushed the deskew shutter in the prior art.

FIG. 3 is a diagram of a paper-feeding mechanism of the present invention.

FIG. 4 and FIG. 5 are schematic drawings of part components of the paper-feeding mechanism at different view angles of the present invention.

FIG. 6 is a diagram of the paper-feeding mechanism when the print medium has pushed the deskew shutter of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 3 and FIG. 4. FIG. 3 is a diagram of a paper-feeding mechanism 50 of the present invention. FIG. 4 and FIG. 5 are schematic drawings of part components of the paper-feeding mechanism 50 at different view angles of the present invention. The paper-feeding mechanism 50 can be utilized in a printer, a fax, a multifunction product (MFP), and so on. The paper-feeding mechanism 50 is utilized for feeding a print medium 52, such as paper or transparency, one sheet at a time into machines so as to proceed to faxes, printouts, copies, and so on. The paper-feeding mechanism 50 further includes a deskew shutter 54, at least one elastic component 56, at least one input roller 58, at least one pinch input roller 60, a paper tray 62, and a pickup roller 64. The paper tray 62 is for positioning the print medium 52. The pickup roller 64 is installed in front of the paper tray 62 for picking up the print medium 52 to the input roller 58 and the pinch input roller 60. The input roller 58 is for picking up the print medium 52. The pinch input roller 60 is for nipping the print medium 52 with the input roller 58. The deskew shutter 54 is installed on a side of the input roller 58 and the pinch input roller 60. The deskew shutter 54 includes a baffle 66, and a flexible pad 68 disposed on the baffle 66 and on an impact surface of the print medium 52 for blocking the print medium 52 before the print medium 52 is nipped by the input roller 58 and the pinch input roller 60 so as to adjust the skew print medium 52. The flexible pad 68 can be made of polyethylene (PE) forming material or sponge material. An end of the elastic component 56 is connected to the deskew shutter 54, and the other end of the elastic component 56 is connected to a fixed end, such as a housing for covering internal components of the paper-feeding mechanism 50. The elastic component 56 provides an elastic force to the deskew shutter 54. The deskew shutter 54 is connected to the elastic component 56 in a rotatable manner. The elastic component 56 can be a spring.

First the print medium 52 is picked up by the pickup roller 64, passes through a paper-feeding route of the paper tray 62, and hits the flexible pad 68 disposed on the baffle 66 of the deskew shutter 54. The print medium 52 has to overcome the elastic force provided by the elastic component 56 connected to the deskew shutter 54 so that the print medium 52 is capable of pushing the baffle 66 of the deskew shutter 54 to enter nip location of the input roller 58 and the pinch input roller 60. If the print medium 52 is positioned exactly, the print medium 52 can overcome the elastic force provided by the elastic component 56 so that the print medium 52 is capable of pushing the flexible pad 68 disposed on the baffle 66 of the deskew shutter 54 to enter nip location of the input roller 58 and the pinch input roller 60. Then the print medium 52 is nipped by the input roller 58 and the pinch input roller 60 together and transmitted to a print area. If the print medium 52 is skew, one leading edge of the print medium 52 hits the flexible pad 68 disposed on the baffle 66 of the deskew shutter 54 first but the leading edge of the print medium 52 can not overcome the elastic force provided by the elastic component 56 on the instant. After the print medium 52 deforms so that two leading edges of the print medium 52 hit the deskew shutter 54, the print medium 52 can overcome the elastic force provided by the elastic component 56. Because the flexible pad 68 is made of deformable and flexible material, such as polyethylene forming material or sponge material. A deformed depression of the flexible pad 68 is formed by a pressure force provided by the print medium 52. The flexible pad 68 can provide more holding force and friction force to hold the leading edge of the print medium 52 on the impact surface of the flexible pad 68. When the two leading edges of the print medium 52 are positioned in alignment, the print medium 52 can overcome the elastic force provided by the elastic component 56 so that the print medium 52 is capable of pushing the deskew shutter 54 to enter nip location of the input roller 58 and the pinch input roller 60. Then the print medium 52 is nipped by the input roller 58 and the pinch input roller 60 together and transmitted to the print area.

When the print medium 52 overcomes the elastic force provided by the elastic component 56 to push the deskew shutter 54 and to enter nip location of the input roller 58 and the pinch input roller 60, the deskew shutter 54 rotates and an inclined angle of the deskew shutter 54 increases, that is, an included angle between the print medium 52 and the deskew shutter 54 decreases. Please refer to FIG. 6. FIG. 6 is a diagram of the paper-feeding mechanism 50 when the print medium 52 has pushed the deskew shutter 54 of the present invention. Because the flexible pad 68 can provide more holding force and friction force to hold the leading edge of the print medium 52 on the impact surface of the flexible pad 68, the print medium 52 can not stray from a normal paper-feeding route. That is, the flexible pad 68 can prevent the print medium 52 from dropping from the deskew shutter 54 and avoids a paper jam situation.

In contrast to the conventional paper-feeding mechanism, the paper-feeding mechanism of the present invention disposes the flexible pad on the deskew shutter for adjusting the skew print medium effectively. This mechanism design increases holding force and friction force to hold the print medium by the deskew shutter. It can increase a suitable range of the elastic component solve the problem of paper jam due to light print medium. The paper-feeding mechanism of the present invention has advantages of low cost, fast transmission speed, a simple control circuit, and avoiding paper jam.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. A paper-feeding mechanism comprising: an input roller for picking up a print medium; a pinch input roller for nipping the print medium with the input roller; a deskew shutter installed on a side of the input roller and the pinch input roller, the deskew shutter comprising a flexible pad for blocking the print medium before the print medium is nipped by the input roller and the pinch input roller so as to adjust the skew print medium; and an elastic component connected to the deskew shutter for providing an elastic force to the deskew shutter, the deskew shutter being connected to the elastic component in a rotatable manner.
 2. The paper-feeding mechanism of claim 1 wherein the deskew shutter comprises a baffle and the flexible pad is disposed on the baffle.
 3. The paper-feeding mechanism of claim 1 wherein the flexible pad is made of polyethylene (PE) forming material.
 4. The paper-feeding mechanism of claim 1 wherein the flexible pad is made of sponge material.
 5. The paper-feeding mechanism of claim 1 wherein the flexible pad continues blocking the print medium after the print medium is nipped by the input roller and the pinch input roller so as to prevent the print medium from dropping from the deskew shutter.
 6. The paper-feeding mechanism of claim 1 wherein the elastic component is a spring.
 7. The paper-feeding mechanism of claim 1 further comprising: a paper tray for positioning the print medium; and a pickup roller installed in front of the paper tray for picking up the print medium to the input roller and the pinch input roller. 